1. Field of the Invention
The present invention relates to a putter head for golf.
2. Description of the Related Art
In putting, the path of a club head in a putting stroke is important, and the orientation of the face surface at the time of impact as well as the position of an impact point (a point of contact between the face surface and the ball at the time of impact) are very important. Putting is hitting a ball by aiming at a small cup on a green, which has complicated inclinations, and if there is any error in the ball hitting direction or the hitting speed, the ball misses the small cup. This is because the trajectory of the ball rolling on the green subtly changes depending on the initial speed of the ball and the hitting direction and further on the green speed, the inclination, and the like. Accordingly, to obtain an excellent result in putting, it is necessary to control the hitting direction and the hitting speed very accurately. For this purpose, it becomes necessary to stabilize the path of the head during the stroke and to very accurately control the orientation of the face surface and the position of the impact point at the time of impact.
To attain the above-described object, a putter head came to be proposed in which three kinds of moment of inertia in the putter head are appropriately set by giving consideration to the characteristic features of the head behavior based on the characteristics of the putting stroke, thereby making it possible to stabilize the path of the head and stabilize the orientation of the face surface and the position of the impact point at the time of impact. In this putter head, it is assumed that the moment of inertia of a first axis that passes through the center of gravity of the head and is parallel to the face surface and a horizontal plane is M1. Also, it is assumed that the moment of inertia of the head about a second axis that is a vertical axis passing though the center of gravity of the head is M2. Further, it is assumed that the moment of inertia of the head about a third axis that passes through the center of gravity of the head and is orthogonal to the first axis and to the second axis is M3. A weight balance is set such that a relationship of M2>M3>M1 is satisfied, and that a value of (M3−M1) is not less than 50 g·cm2 and not more than 1500 g·cm2 (refer to JP-A-2005-124806 (page 6, FIG. 1)).